Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.3.14 (ATP synthase)
7,042 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Effect of respiration toxins is studied on some properties of mitochondrial membranes and functions connected with ion transport for the expence of ATP energy. The combination of three respiration inhibitors (cyanide, antimycin and rotenone) was shown to develope the following effects: 1) the inhibition of K+ accumulation by mitochondria at the presence of ATP and valinomycin; 2) the decrease in acidification of non-mitochondrial space, accompanying to the K+ transport; 3) the activation of latent mitochondrial ATPase; 4) the inhibition of DNP-stimulated ATPase; 5) the inhibition of mitochondria swelling, caused by K+, Ca2+, or dimethyldibenzylammonium (DDA+) at the presence of ATP+phopshate (or acetate); 6) the stimulation of passive mitochondria swelling in 0.1 MNH4NO3; 7) the inhibition of ATP-induced contraction of mitochondria, swelling in NH4NO3. The data obtained are discussed in a wiev of the conception, which suggests that the attaching of inhibitors to respiration enzymes changes the configuration of the latters, thus disturbing natural structural bond of these enzymes with other protein components of the membrane. The latter can result in the impair of electroisolating membrane properties, in the increase of its conductivity for H+ and other ions, and in the decrease of Vm values of some enzymatic reaction, which are not directly connected with the respiration chain (such as ATPase reaction).
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PMID:[Respiration toxins as inhibitors of ion transport, supported by ATP hydrolysis, in mitochondria]. 12 71

1. A study is presented of the mitochondrial NADH content during controlled (state 4) and active (state 3) pyruvate oxidation by blowfly flight-muscle mitochondria. The results confirm and extend those of an earlier study (Hansford, 1972), which indicated an increased reduction in state 3. Nicotinamide nucleotide is normally highly oxidized during state 4; however, there can be substantial reduction in the presence of carnitine or high concentrations of proline, or on lengthy incubation in the presence of either of the systems used to generate intramitochondrial tricarboxylate-cycle intermediate. 2. Omission of phosphate leads to substantial reduction and this can be reversed by adding phosphate or acetate. 3. Estimations of NAD-+ and NADH in fly thoraces show a marked increase in NADH on flight, tending to corroborate the results of mitochondrial experiments and testifying to the importance of dehydrogenase activation in this tissue. 4. Determination of intramitochondrial adenine nucleotides reveals a total of 4-5 nmol/mg of protein, and an ADP content of less than 0.1 nmol/mg during state 4 oxidation of pyruvate and proline. ATP content is found to increase slowly during state 4 and this is attributed to the net phosphorylation of AMP. 5. The uncoupling agent carbonyl cyanide p=trifluoromethoxyphenylhydrazone leads to hydrolysis of some, but not all, of the mitochondrial ATP. Studies of mitochondrial ATPase (adenosine triphosphatase), measured by external pH change, show that it is inactive unless the mitochondria are allowed to respire for several minutes in state 4 in the presence of phosphate before the addition of carbonyl cyanide p-trifluoromethoxyphenylhydrazone. It is suggested that phosphate uptake is essential for maximal ATPase activity. 6. Studies of the fluorescence of the fluorochrome 8-anilino-1-naphthalensulphonic acid suggest that the energy status of the mitochondrion is high during state 4-pyruvate oxidattion, and decrease slightly in state 3. The implications of these findings are discussed.
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PMID:The control of tricarboxylate-cycle oxidations in blowfly flight muscle. The oxidized and reduced nicotinamide-adenine dinucleotide content of flight muscle and isolated mitochondria, the adenosine triphosphate and adenosine diphosphate content of mitochondria, and the energy status of the mitochondria during controlled respiration. 16 20

Methanogenesis is restricted to a group of prokaryotic microorganisms which thrive in strictly anaerobic habitats where they play an indispensable role in the anaerobic food chain. Methanogenic bacteria possess a number of unique cofactors and coenzymes that play an important role in their specialized metabolism. Methanogenesis from a number of simple substrates such as H2 + CO2, formate, methanol, methylamines, and acetate is associated with the generation of transmembrane electrochemical gradients of protons and sodium ions which serve as driving force for a number of processes such as the synthesis of ATP via an ATP synthase, reverse electron transfer, and solute uptake. Several unique reactions of the methanogenic pathways have been identified that are involved in energy transduction. Their role and importance for the methanogenic metabolism are described.
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PMID:Energetics of methanogenesis studied in vesicular systems. 145 85

Intracellular acidic compartments serve several functions, including uptake of nutrients, processing and sorting of secreted and membrane-bound proteins, and even entry of viruses into cells. In this study, we examined the distribution of acidic compartments in normal human keratinocytes cultured in serum-free medium. Acridine orange was used to stain acidic organelles (red fluorescence), and adherent cells were evaluated by fluorescence microscopy and by interactive laser cytometry (ILC). Keratinocytes cultured in low [Ca++] (0.15 mM) exhibited morphologic characteristics associated with basal cells; red acidic vesicles in these cells were aggregated around the nucleus, sparing the peripheral cytoplasm. After 24 h of culture in high [Ca++] (1.5 mM) keratinocytes showed morphologic changes associated with differentiated cells, including increased number and dispersal of red vesicles to the periphery of the cytoplasm. Keratinocytes cultured in 0.15 mM [Ca++], but treated with phorbol 12-myristate 13-acetate (PMA, 5-100 ng/ml) to induce terminal differentiation, developed similar features. Incubation in media with either high [Ca++] or PMA also induced radial extension of the microtubule network, suggesting that the distribution of acidic organelles occurs along this network. Finally, crude keratinocyte membranes were evaluated by radioactive assay for the presence of three ion-translocating ATPase activities, plasma membrane Na/K ATPase, mitochondrial ATPase, and vacuolar H+ pump ATPase, the latter being the activity responsible for acidification of intracellular compartments. Both basaloid and differentiated keratinocytes exhibited similar vacuolar H+ pump ATPase activity, as measured by its sensitivity to bafilomycin.
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PMID:Increased number and microtubule-associated dispersal of acidic intracellular compartments accompany differentiation of cultured human keratinocytes. 153 43

Fluorometry and high-performance liquid chromatography were used to measure the content of free CoA and the esters of acetate, malonate, succinate, and long-chain fatty acids in isolated perifused rat pancreatic islets exposed to 25 mM glucose or a mixture of fuels (25 mM glucose plus 10 mM glutamine, 10 mM lactate, and 1 mM pyruvate) to assess the role of intermediates of lipid metabolism as candidate metabolic coupling factors in the mechanism of fuel-induced insulin secretion. Insulin secretion was stimulated in a biphasic manner with the fuel mixture, showing twice the potency compared with high glucose alone. Islets perifused for 3 min with high glucose alone or the fuel mixture compared with 2.5 mM glucose showed a significant increase in malonyl-CoA and succinyl-CoA and a decrease in acetyl-CoA. Free CoA and long-chain acyl-CoA levels were unaltered. Perifused islets stimulated with 25 mM glucose for 30 min showed a significant increase in succinyl-CoA and long-chain acyl-CoA and decrease in acetyl-CoA, whereas malonyl-CoA was not affected. However, when islets were stimulated by the fuel mixture for 30 min, malonyl-CoA was maintained at a high level, and the change in succinyl-CoA and long-chain acyl-CoA was similar to that observed in islets stimulated with 25 mM glucose alone. The acetyl-CoA concentration in the islets stimulated with the fuel mixture decreased slightly. These results confirm the viability of the hypothesis that malonyl-CoA and long-chain acyl-CoA serve as metabolic coupling factors in signal transduction when islets are stimulated by high glucose or glucose combined with other fuels.
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PMID:Content of CoA-esters in perifused rat islets stimulated by glucose and other fuels. 199 74

After studying the effects of almitrine, a new kind of ATPase/ATP synthase inhibitor, on two kinds of isolated mammalian mitochondrion, we have observed that: (1) Almitrine inhibits oligomycin-sensitive ATPase; it decreases the ATP/O value of oxidative phosphorylations without any change in the magnitude of delta mu H+. (2) Almitrine increases the mechanistic H+/ATP stoichiometry of ATPase as shown by measuring either (i) the extent of potassium acetate and of potassium phosphate accumulation sustained by ATP utilisation, or (ii) the electrical charge/ATP (K+/ATP) ratio at steady-state of ATPase activity. (3) Rat liver mitochondria are at least 10-times more sensitive to almitrine than beef heart mitochondria. (4) The change in H+/ATP stoichiometry induced by almitrine depends on the magnitude of the flux through ATPase. The inhibitory effect of almitrine on ATPase/ATP synthase complex, as a consequence of such an H+/ATP stoichiometry change, is discussed.
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PMID:Flux-dependent increase in the stoichiometry of charge translocation by mitochondrial ATPase/ATP synthase induced by almitrine. 216 21

1. The cytoplasmic membrane ionic current of cells of Rhodobacter capsulatus, washed to lower the endogenous K+ concentration, had a non-linear dependence on the membrane potential measured during photosynthetic illumination. Treatment of the cells with venturicidin, an inhibitor of the H(+)-ATP synthase, increased the membrane potential and decreased the membrane ionic current at values of membrane potential below a threshold. 2. The addition of K+ or Rb+, but not of Na+, led to an increase in the membrane ionic current and a decrease in the membrane potential in either the presence or absence of venturicidin. Approximately 0.4 mM K+ or 2.0 mM Rb+ led to a half-maximal response. At saturating concentrations of K+ and Rb+, the membrane ionic currents were similar. The membrane ionic currents due to K+ and Rb+ were not additive. The K(+)-dependent and Rb(+)-dependent ionic currents had a non-linear relationship with membrane potential: the alkali cations only increased the ionic current when the membrane potential lay above a threshold value. The presence of 1 mM Cs+ did not lead to an increase in the membrane ionic current but it had the effect of inhibiting the membrane ionic current due to either K+ or Rb+. 3. Photosynthetic illumination in the presence of either K+ or Rb+, and weak acids such as acetate, led to a decrease in light-scattering by the cells. This was attributed to the uptake of potassium or rubidium acetate and a corresponding increase in osmotic strength in the cytoplasm. 4. The addition of NH4+ also led to an increase in membrane ionic current and to a decrease in membrane potential (half-maximal at 2.0 mM NH4+). The relationship between the NH4(+)-dependent ionic currents and the membrane potential was similar to that for K+. The NH4(+)-dependent and K(+)-dependent ionic current were not additive. However, illumination in the presence of NH4+ and acetate did not lead to significant light-scattering changes. The NH4(+)-dependent membrane ionic current was inhibited by 1 mM Cs+ but not by 50 microM methylamine. 5. It is proposed that the K(+)-dependent membrane ionic current is catalysed by a low-affinity K(+)-transport system such as that described in Rb. capsulatus [Jasper, P. (1978) J. Bacteriol. 133, 1314-1322]. The possibility is considered that, as well as Rb+, this transport system can also operate with NH4+. However, in our experimental conditions NH4+ uptake is followed by NH3 efflux.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Membrane ionic currents in Rhodobacter capsulatus. Evidence for electrophoretic transport of K+, Rb+ and NH4+. 240 35

A simple analytical procedure for comparing the rates of inactivation of an enzyme in the presence and absence of its substrate is proposed. The rapid inactivation of yeast F1-ATPase during the catalytic reaction was found to be due to certain anions rather than due to ATP or ADP. MgATP failed to protect the enzyme but substituting sulfate, acetate, bicarbonate, or N-tris(hydroxymethyl)methyl-2-aminoethane sulfonate anions and preincubation with ADP prevented the inactivation.
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PMID:Use of Swinbourne plots to study potential suicide substrates: effects of ATP and ADP on yeast mitochondrial F1-ATPase. 286 16

One subunit of the membrane portion of yeast ATP synthase was purified. Structural data are reported. This subunit (subunit 4) is the fourth polypeptide of the complex when classifying subunits in order of decreasing molecular mass. Its apparent relative molecular mass is about 25,000. The polypeptide was extracted from the complex with a mixture of chloroform/methanol (1/1) and 0.5 M pyridinium acetate pH 6.0. Purification was performed with a combination of gel permeation chromatography on Sephadex G-75 and high-performance gel permeation chromatography with aqueous solvents containing 5% sodium dodecyl sulfate. The amino acid composition is reported here. The following sequence of the NH2-terminal ten residues was determined: Met-Ser-Ser-Thr-Pro-Glu-Lys-Gln-Thr-Asp.
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PMID:Subunit 4 of ATP synthase (F0F1) from yeast mitochondria. Purification, amino-acid composition and partial N-terminal sequence. 288 7

The effects of alpha-tocopherol and its derivatives on the energy metabolism in mitochondria were studied. It was shown that alpha-tocopherol derivatives with short hydrocarbon chain produce uncoupling effects, while alpha-tocopherol itself as well as its long-chain derivatives (tocopheryl acetate and tocopheryl stearate) exert no effect. All the derivatives studied produced an inhibitory effect on DNP-stimulated mitochondrial ATPase. As far as these compounds did not influence the activity of mitochondrial F1 factor, it was concluded that the effects of the compounds were due to membrane modification.
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PMID:[Effect of alpha-tocopherol and its derivatives on ATPase activity and oxidative phosphorylation in rat liver mitochondria]. 295 31


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